I sincerely believe that if you stop and think you will not fire.
Case in point: As a teenager I once drew on a man trying to enter our house. My dog had alerted. I grabbed my Single Six that was officially unloaded and followed. The door slammed shut. I opened it (ok, stupid, and green, but I was a kid) and there was the man just standing there. I shot over his head. I cocked, leveled it at his chest, and had three pounds on the five pound trigger when he turned and ran. The reason I didn't fire? I thought. I delayed long enough to get the jitters, the what-ifs, the second guesses.
Fast forward to a couple years ago. I found myself in a much scarier situation -- a dog attack. Two canines came in low and fast. In one smooth motion I drew, sighted, and fired. Recovered, fired. Recovered, fired. I shot three times, counting my shots as I had trained.
I didn't hit them. Too low, too fast, and I hadn't trained for that. The training has since been remedied but that's not the point here. I didn't think; I just did.
It's like I tell my seven year old when I'm being Sensei Dad: Don't think, just do. If you have to think you'll be slow, and if you're slow you'll lose. He stopped thinking, got past my defense, and split my lower eyelid. I simply was not prepared for that explosion of speed, especially compared to what he had been doing, all because of thought.
The way I figure it, if your instincts are going to take over, let them. But, train yourself to draw and mentally remove yourself from the situation.
In other words, there is no room for emotion, thought, or anything which might interfere with efficiency. Done right, your conscious mind will remove itself from the situation and become a disinterested observer who is cool and calm enough to count shots.
Save the shakes for afterward. If you have the shakes during, that's adrenaline that could be better utilized in the fight.
I'm sorry if I sound arrogant; this is something I have come to truly believe. I have more experience than most private citizens and way less experience than others. And, this is what my experience tells me.
Josh <><